the more surface area that’s contacted between the driver and the fastener, the more friction and the better they hold on to the automatic drivers used to assemble the devices. On such a tiny screw the center pin probably adds an extra 20% or more surface area.

I don’t know if that’s absolutely the reason but if they wanted to keep people out they could easily make a custom head that looked like the Apple logo or something. Nintendo has used tri-wing screws for decades because they expressly do want to keep people out of their devices. You can stop get a tri-wing driver but you have to special order it.